Every node in the Ethereum network holds a copy of the blockchain. We need to make sure that nodes cannot tamper with the blockchain, and we also need a mechanism to check whether a block is valid or not. And also, if we encounter two different valid blockchains, we need to have a way to find out which one to choose.
Ethereum uses the proof-of-work consensus protocol to keep the blockchain tamper-proof. A proof-of-work system involves solving a complex puzzle to create a new block. Solving the puzzle should require a significant amount of computational power thereby making it difficult to create blocks. The process of creating blocks in the proof-of-work system is called mining. Miners are the nodes in the network that mine blocks. ...
